1. Field of the Invention
The present invention relates in general to an in-plane switching mode liquid crystal display (IPS-LCD). In particular, the present invention relates to an electrode array of an IPS-LCD and methods of fabrication thereof.
2. Description of the Related Art
Liquid crystal displays (LCDs) may be classified by the orientation of the liquid crystal molecules between the spaced apart substrates. In a conventional twisted nematic (TN)-LCD, the liquid crystal molecules are twisted between the two substrates. In contrast, in an in-plane switching mode (IPS)-LCD, common electrodes and pixel electrodes are formed on a lower glass substrate (TFT substrate) and an in-plane electrode field therebetween is generated to rearrange the liquid crystal molecules along the electrode field. Accordingly, the IPS-LCD has been used or suggested for improving drawbacks of the conventional TN-LCD, such as a very narrow viewing angle and a low contrast ratio.
In order to achieve a better result of the in-plane electrode field, various designs for an electrode array of the IPS-LCD are built to solve the problems such as an insufficient aperture ratio, crosstalk produced between data lines and common electrodes, and increasing masks used in patterning. Specially, JP 56-91277 discloses with respect to a comb-shaped electrode array. Please refer to FIG. 1A, which shows a circuit structure of a conventional IPS-LCD. The IPS-LCD has gate lines 1, data lines 5 crossing over the gate lines 1, a thin film transistor (TFT) 2 formed at the intersection of the gate line 1 and the data line 5, a comb-shaped pixel electrode 4, and a comb-shaped common electrode 3. In the TFT 2, a source electrode is electrically connected to the data line 5, and a drain electrode is electrically connected to one end of the comb-shaped pixel electrode 4. The common electrode 3 has a bar parallel to the gate line 1 and a plurality of comb-teeth extending away from the bar and parallel to the data line 5 toward a first direction. The pixel electrode 4 has a bar parallel to the gate line 1 and a plurality of comb-teeth extending away from the bar and parallel to the data line 5 toward a second direction. The comb-teeth of the common electrode 3 are separated from the comb-teeth of the pixel electrode 4 by a predetermined distance. When the common electrode 3 and the pixel electrode 4 are respectively grounded, an in-plain electrode field is generated therebetween.
In the comb-shaped electrode array, for increasing the storage of signals, a storage capacitor can be fabricated on the bar of the common electrode 3. However, no reference discloses with respect to a technique for employing a conductor to cover the storage capacitor and connect to the pixel electrode. As well, with reference to a cross-sectional diagram as shown in FIG. 1B, crosstalk easily occurs between the comb-teeth of the common electrode 3 and the data line 5.
An object of the present invention is to provide a comb-shaped electrode array of an IPS-LCD to increase the storage of signals.
Another object of the present invention is to provide a comb-shaped electrode array of an IPS-LCD to eliminates the crosstalk produced between the common electrode and the data line.
The electrode array of the IPS-LCD in the present invention includes:
a plurality of gate lines made by patterning a bottom-metal layer and disposed in an X-direction;
a plurality of data lines made by patterning a inter-metal layer and disposed in a Y-direction, wherein two adjacent data lines and two adjacent gate lines constitute a pixel area;
a plurality of comb-shaped common electrodes made by patterning the bottom-metal layer and respectively disposed in each pixel area, wherein each comb-shaped common electrode comprises a bar parallel to the gate line and a plurality of comb-teeth extending in a first Y-direction
a plurality of comb-shaped pixel electrode made by patterning the inter-metal layer and respectively disposed in each pixel area, wherein each comb-shaped pixel electrode comprises a bar parallel to the gate line and a plurality of comb-teeth which extend in a second Y-direction and are inter-digitated with the comb-teeth of the common electrode;
a connecting layer made by patterning a top-metal layer to electrically connect with one end of the comb-teeth of the pixel electrode and cover part of the bar of the common electrode
a first strip-shaped metal-shielding layer made by patterning the top-metal layer and disposed over the rightmost comb-tooth of the common electrode, wherein the first metal-shielding layer extends to electrically connect with the bar of the common electrode; and
a second strip-shaped metal-shielding layer made by patterning the top-metal layer and disposed over the leftmost comb-tooth of the common electrode, wherein the first metal-shielding layer extends to electrically connect with the bar of the common electrode.
It is an advantage of the present invention that the connecting layer can increase the signal storage capacity. Also, the strip-shaped metal-shielding layers disposed over the comb-teeth of the common electrode can eliminate crosstalk.